The present invention relates generally to semiconductor device fabrication and, more particularly, to electrostatic discharge (ESD) circuits for protecting a power pad or other low frequency input/output (I/O) pad, methods of fabricating an ESD protection circuit, methods for providing ESD protection, and design structures for an ESD protection circuit.
Modern electronics achieve high levels of functionality in small form factors by integrating multiple functions onto a single chip. A common fabrication process that allows high levels of integration at a relatively low cost is complementary metal-oxide-semiconductor (CMOS). CMOS processes build a combination of p-type and n-type metal-oxide-semiconductor field-effect transistors (MOSFETs) to implement logic gates and other types of digital circuits, as well as analog circuits.
Chips may be exposed to ESD events leading to potentially large and damaging currents within the integrated circuit. Increasing integration densities and performance demands on CMOS chips have resulted in reduced device dimensions, which has increased the susceptibility of integrated circuits to ESD events. Manufacturers, assemblers, and users of integrated circuits must take precautions to avoid unintentionally causing ESD events. For example, ESD prevention can be incorporated into the integrated circuit and may include special design techniques for I/O pins and pads, as well as supply pads, to prevent damage to the chip during handling between the time that the chip is manufactured until the time that the chip is installed on a circuit board and while the chip is installed on the circuit board. ESD protection circuits direct the current of an ESD event away from the internal circuits of the chip.
CMOS circuit applications require ESD protection circuits that have fast transient turn on times and that clamp the ESD pulse to a low enough voltage to prevent damage to the integrated circuit. ESD protection circuits must also be able to withstand sufficient ESD current levels so as to avoid being damaged by the ESD event, while preferably consuming minimal chip area.
Therefore, improved ESD protection circuits for CMOS circuit applications, methods for providing ESD protection, methods of fabricating an ESD protection circuit, and design structures for ESD protection circuits are needed for protecting integrated circuits against ESD events.